You should fence yourself somehow as quickly as your finances allow you. And train your puppy for the sound inside the house. You need recording for that. Use dictaphone for recording. A recorded sound which causes some sort of great excitemnt/irritation/anxiety in your dog can be replayed at the lower sound level first, then louder, and louder. Ask your puppy to sit while he listens. The reason for doing it - to stop your puppy living in anticipation of that sound. Secondly, train your puppy to meet horses and carriage coming towards you. You should come to the road with your puppy and wait for one. Train him to keep in sitting position until the carriage dissapears. Walk him on the side of the road if possible and train him "heel" while carriages are passing by, try to find out what exactly is so interesting for him. It very well could not the horses but the sound of the wheels and their movement be so attractive for him, similar to the interest dogs pay to bicycles, horses only announce it. Meet him with horses (keeping distance, of course) and bicycles separately in places most certainly you will find them, it might help him to lose his interest. But, mainly I'd press on obedience, he must return with your first recall, he must sit when he was told to sit, and he must walk without pulling the lead when he was told to heel. If he does it badly in other distractive situations, he wouldn't be obedient when something really makes him nuts.